The prior art is familiar with certain techniques for inspecting the quality of endless profiles by contactless means. For reliable quality inspection, in particular of continuous profiles, analysis by means of electronic digital image processing has been recently established. Irradiating the surface of the profile by means of a suitable light source and detecting the reflected radiation by an electronic camera device with subsequent electronic image processing provides feedback on the dimensioning and tolerances of an object and on the finish of its surface.
U.S. Pat. No. 6,064,759 discloses the measuring of an object, a light source for structured light, which is arranged obliquely at an angle to the surface of the object, and a recording device arranged perpendicularly to the surface of the object being used. The light source for structured light is a laser. The evaluation of the image points recorded from the object is based on the known methods of digital image processing.
DE 103 28 537 A1 discloses an apparatus and a method for measuring the dimension of an object. In this case, radiation is directed onto the object past a light blocking element, so that a so-called sharp light edge is formed on the surface of the object. A suitable sensor device captures the radiation reflected by the sharp light edge and converts it into image data, with which an image evaluation is subsequently carried out for determining the dimensions of the object.
DE 101 20 430 A1 shows an apparatus for the automatic surface inspection of profiles with electronic camera devices. A continuous profile is passed through a so-called light ring and thereby irradiated with light along its circumference by corresponding light sources which are arranged along the light ring. Electronic camera devices are provided adjacent the light ring, in order to capture light which is reflected by the surface of the profile, in order subsequently to carry out an evaluation of the image points for a surface inspection. However, this apparatus has the disadvantage that, to achieve reliable measuring results, an exact position of the camera devices relative to the profile to be measured must be known, which requires complex setting of the apparatus or complex calibration.
It is an aim of the invention to simplify surface inspection of an object, in particular by means of digital image processing, with regard to equipment setting.